There is a demand that operating efficiency at the photomechanical process stage be improved in the field of printing reproduction to cope with the variety and complexity of prints.
There have been attempts to improve operating efficiency by carrying out operations under lighter circumstances during the page make-up stage and dot to dot work stage in particular. For this purpose, there have been developed exposure printers and silver halide photographic materials for plate making which can be handled under the substantially bright room conditions.
The term "silver halide photographic material for the bright room condition" as used herein refers to a photographic material which allows light containing no ultraviolet light component and having a wavelength of at least 400 nm to be used as safelight.
Heretofore, dyes capable of absorbing visible light have been added to a hydrophilic colloid layer which is farther away from the support than the sensitive silver halide emulsion layers, to increase safety against the above safelight. When the layer containing these dyes functions as a filter layer, it is necessary that the layer is selectively colored and that other layers are substantially not colored. This is because when the emulsion layers are substantially colored, not only does the coloration have an adverse photographic effect on the emulsion layers, but also the effect of the dye-containing layer as a filter layer is reduced. There are also specific problems that spread and chokability, tone variability and outline type (open face) deteriorate in dot to dot work in particular.
As a means for solving these problems, there is known a method wherein the dyes are localized in a specific layer by using dyes having a sulfo group or a carboxyl group (i.e., so-called acid dyes) as mordants.
Examples of such mordants include: ethylenically unsaturated polymers having a dialkylaminoalkyl ester residual group described in British Patent 685,475; reaction products of polyvinyl alkyl ketones with aminoguanidine described in British Patent 850,281; and vinylpyridine polymers and vinylpyridinium cation polymers described in U.S. Pat. Nos. 2,548,564, 2,484,430, 3,148,061 and 3,756,814. Cationic polymer mordants having a sec- or tert-amino group, a nitrogen-containing heterocyclic group or a quaternary cationic group thereof, are used to mordant effectively the acid dyes.
As a means for retaining the dyes in a specific layer of the photographic material, there is known a method wherein the dyes are allowed to exist as dispersed solids as described in JP-A-56-12639 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-55-155350, JP-A-55-155351, JP-A-52-92716, JP-A-59-193447, JP-A-61-198148, JP-A-63-197943, JP-A-63-27838, JP-A-64-40827, European Patents 0015601Bl and 0276566Al and PCT(WO) 88/04794.
However, there is still the problem that it is impossible that the tone reproducibility required for photographic materials for dot to dot work cannot be fully satisfied.
When a selectively colored filter layer is provided and the emulsion layers are not colored, a larger amount of a dye for absorbing visible light must be used in comparison with the photographic materials in which the emulsion layers are colored to retain safety against safelight and safety against external light from backing layers. However, when the amount of the dye is too large, problems of tone variability deterioration and residual color after processing are caused.